1. Field of the Invention
The present invention relates to an electrical outlet set and, more particularly, to a power supply status control circuit of electrical outlet set, which is designed for use with a computer and the related peripheral apparatus.
2. Description of the Prior Art
A conventional electrical outlet set for use with a computer is generally comprised of a main receptacle and a plurality of auxiliary receptacles connected in parallel to the main receptacle. After connection of the electrical outlet set, the main and auxiliary receptacles provide the necessary working voltage to the computer and the related peripheral apparatus (modem, printer, and etc.) installed therein. However, this conventional electrical outlet set provides only one single power supply status, i.e., all the receptacles are maintained electrically connected after connection of the electrical outlet set to city power supply. Therefore, when the computer that is connected to the main receptacle is shut down, the peripheral apparatus that are respectively connected to the auxiliary receptacles must be separately turned off.
FIG. 1 shows an electrical outlet set according to the prior art. This structure of electrical outlet set 1 comprises a plurality of receptacles 2, and a plurality of on/off switches 3 adapted to switch on/off the receptacles 2 respectively. After each use of the computer, the user controls the on/off switches 3 to turn off the respective peripheral apparatus. This manual peripheral apparatus control operation is still inconvenient. The peripheral apparatus cannot be automatically turned off when shutting down the computer.
The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a power supply status control circuit for an electrical outlet set, which automatically switches off all auxiliary receptacles when the user shuts down the computer at the main receptacle. The power supply status control circuit of the present invention is used in an electric outlet set for computer, the electric outlet set comprising a main receptacle and a plurality of auxiliary receptacles, the main receptacle and the auxiliary receptacles each having a first end and a second end respectively connected to two opposite ends of AC power supply. The power supply status control circuit comprises a DC power circuit connected to AC power supply and adapted to convert AC power supply into DC power supply (VCC) for output; a first fuse, the fuse having a first end and a second end respectively connected to the second end of the main receptacle and one end of AC power supply, the fuse having a predetermined resistance value; an amplifier adapted to amplify the voltage value of the electricity passing through the first fuse, the amplifier having an input end connected to the second end of the first fuse and an output end; a comparator adapted to compare the voltage value of the electric current passing through the first fuse with a reference voltage, the comparator having an input end connected to the output end of the amplifier and an output end for output of comparison result; an electrically-controlled switch unit connected between the second end of the main receptacle and the second end of each of the auxiliary receptacles, the electrically-controlled switch unit comprising a signal input end connected to the output end of the comparator to receive the output voltage of the comparator for on/off control. When the electric apparatus at the main receptacle is turned off, the electrically controlled switch unit is switched off, thereby causing the second end of each of the auxiliary receptacles to be electrically disconnected from the second end of the main receptacle. When the electric apparatus at the main receptacle is turned on, the electrically controlled switch unit is switched on, thereby causing the second end of each of the auxiliary receptacles to be electrically connected to the second end of the main receptacle for enabling the auxiliary receptacles to obtain power supply.